Owing to the increasing complexity of applications in the field of motor-vehicle information electronics, which can now be referred to as being multimedia, new concepts have become necessary for the networking of different appliances.
For example, it should be possible for at least the car radio, mobile telephone and navigation system to communicate bidirectionally with one another so that, for example, the reproduction of music by the car radio can be muted and the mobile radio link can be operated via the radio loudspeaker when the user wishes to make a telephone call. However, this is obviously only a very simple application and the multimedia network of on-board electronics is subject to virtually no limits in order to satisfy the customer demand.
In order to satisfy the complex requirements, optical data transmission is being introduced for these connections in the automobile field. In this context, a new standard called MOST® has been developed for this purpose. The specifications for the MOST® standard have been published as the “MAMAC Specification” Rev 1.0, November 2002, Version 1.0-00 at http://www.mostnet.de/downloads/Specifications/MAMACSpecification—1V0-00.pdf and at http://www.mostnet.de/downloads/Specifications/MOST%20Physical%20Layer%20Specification/010223 WgPhy Drawings.zip. Reference is hereby made to the abovementioned specifications, and their entire content is included by reference in the subject matter of this disclosure.
Optical MOST® connector assemblies are designed for the connection of at least two optical waveguides and typically have an optical connector for connection to a corresponding mating connection, and two electrooptical transducers. In one frequently used type of MOST® connector assembly, the transducers are not integrated in the connector housing or fitted directly to it, but are at a distance from it, even though the connector and the transducer are typically soldered on the same circuit board. The connector and the transducer in this embodiment are optically connected to one another by short optical plastic fiber lengths, which are sometimes also referred to in specialist jargon as pigtails.
This physical separation of the connector and of the transducer is used, inter alia, for decoupling, but results in a wide range of problems.
First of all, the fiber lengths are normally attached to the transducers individually. For this purpose, the fiber lengths typically have bayonet-like fittings, for example known “BNC connectors”. However, these are really small and are thus complex to produce, are sensitive, and are difficult to handle. Furthermore, each fiber section must disadvantageously be attached individually with a combined pushing and turning movement.
Furthermore, in the case of automotive applications, there is a requirement for good resistance to vibration, which these bayonet fittings do not adequately comply with. On the contrary, in some circumstances, they have a tendency to become loose when subject to vibration.
In order to avoid this problem, attempts have been made to secure the bayonet fittings against shaking loose by means of an adhesive. Once again, however, this results in a large number of other problems.
Specifically, if the arrangement is delivered ready-assembled to the customer, for example a car electronics manufacturer and if the bayonet fittings are appropriately secured, the plastic fiber lengths are located on the transducers during soldering, and this can lead to an adverse effect on the adhesive bonding on the fibers, because of the heat that is introduced. If, on the other hand, the arrangement is delivered individually, the customer has to deal with the difficulties of connection of the fibers. Apart from this, there is no assurance that the adhesives will last for many years, to many decades, in the severe operational conditions in the automobile field.
Furthermore, adhesively bonded arrangements such as these result in maintenance difficulties.
Bearing in mind the enormous competitive pressure in this market, this situation is undesirable. It is therefore surprising that it has not yet been possible to find any satisfactory solution.
The aim of the invention, in particular, is accordingly to improve the connector assemblies of the type mentioned above, and to overcome the disadvantages mentioned above.
An optical link module is known from U.S. Pat. No. 5,647,042 (Ochiai et al.) wherein a standard optical fiber connector is connected to an optoelectronic conversion means via a single optical fiber and a coupling means. The connection is by a metal plate spring. This system appears to be a too sensitive one and a too costy one for automotive applications. Furthermore, Ochiai et al. starts from a coupling means for an optical fiber and does not suggest an amended fixation of a pair of pig-tails to a pair of transducers.